The present invention relates to an aseptic closure for containers of liquids, particularly beverages.
It is well-known that there is a strongly felt need to provide containers for beverages with aseptic closures which allow to remove part of the contents and then ensure adequate sealing upon re-closure.
This is the case, for example, of containers for sodium replenishment beverages, i.e., beverages rich in mineral salts, which are widely used and appreciated by people who practice sports and need to replace the substances lost with perspiration.
In particular, the user must not be forced to drink the beverage all at once; the closure, after being opened, must allow re-closure so that the beverage can be preserved and can be consumed over a short period of time, keeping its characteristics unchanged.
The containers are normally constituted by a bottle-shaped container which has a neck and an opening through which the beverage is automatically introduced during packaging; a closure is subsequently fixed in order to provide aseptic closure.
Currently, one type of these closures is constituted by a main body which is provided with a threaded ring and must be screwed onto the neck of the container; a tubular projection protrudes axially from the main body.
The projection is coupled to an upper closure which is also tubular and can slide externally along the projection.
The upper closure is shaped complementarily to the projection and is provided with a flat wall in which there is provided a central hole through which the beverage can flow out.
Radial bridges protrude from the internal walls of the projection, proximate to its upper end, and support an internal island which is coaxial to the projection and whose dimensions conveniently match those of the hole formed in the upper closure and are such as to have no slack.
In this way, the aseptic closure is perfectly closed when the upper closure, which can slide along the projection, is lowered completely and the hole formed in the wall is closed hermetically by the island arranged inside the projection.
In order to make the beverage flow out from the container, it is instead sufficient to slide upward the upper closure, so as to release the internal island, disengaging it from the rims of the hole.
Once the user has lifted the upper closure, he can drink directly by bringing the closure to his mouth.
The main body of the closure is normally screwed onto the neck of the container, and as a guarantee of the integrity of the package it can be disengaged from the container only after separating it, by tearing, from a strip-ring of the per se known type, which is inserted so as to wrap around the neck of the container.
The upper closure is further provided with a cap-like closure element which covers it, so as to protect the region that is placed in the user's mouth.
The above-described closure effectively performs its task, but unfortunately suffers the drawback of making the sterilization step difficult.
According to statutory provisions, the beverage must in fact be stored in a fully sterilized environment and accordingly the inside of the closure must be sterilized beforehand, before it is screwed onto the neck of the container.
This sterilization is normally performed by spraying sanitizing liquid, but due to the presence of the radial bridges and of the internal disk which protrude monolithically from the upper end of the projection, the liquid is never able to reach all the internal points of the closure.
Up to now, this drawback has been dealt with by separating the liquid, which must be confined inside the container alone, from the closure, by providing on the opening of the neck a disk made of a paper-aluminum bonded material which acts as a diaphragm and is fixed, for example, along the rims by gluing.
In this manner, the liquid remains inside the container and cannot access the internal region of the closure, unless the paper-aluminum disk is removed after tearing the strip-ring and unscrewing the main body of the closure.
This operation is in any case awkward for the user.
Another type of conventional closure comprises a main body provided with a threaded ring, arranged to be associated with the neck of a container, from which a tubular projection protrudes which is coupled to an upper closure.
Proximate to the main body, radial bridges protrude from the internal wall of the projection and support an internal island so as to form, together with the island, axial channels for the passage of the liquid of the container.
The upper closure is tubular and forms, with its lower end, an annular flow control element which provides a seal between the outer wall of the island and the internal wall of the tubular projection.
While solving the above-cited sterilization problems (when the upper closure is lowered, the liquid passage channels are closed by the flow control element and the sanitizing liquid encounters the internal island, the radial bridges and the flow control element), the above-described closure has given rise to other problems linked to the double sealing wall, which does not always ensure a hermetic seal due to molding tolerances.